function swap(id, is_on) {
	if(is_on)
		document.getElementById(id).src = 'images/' + id + '_on.png';
	else
		document.getElementById(id).src = 'images/' + id + '_off.png';
}

function validate(form) {
	var name = form.name.value;
	var email = form.email.value;
	var message = form.message.value;
	if(name == '') {
		alert('Please enter your name');
		form.name.focus();
		return false;
	} else if (!validateEmail(email)) {
		alert('Please enter a valid email address');
		form.email.focus();
		return false;
	} else if(message == '') {
		alert('Please enter your message');
		form.comments.focus();
		return false;			
	}
	return true;
}
	
function validateEmail(email) {
	var exp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	return email.match(exp);
}

function showBillingForm() {
		
}